ANything is possible BUT I had EXACTLY the same issue after my GL1500 sat for four years. I took it to my regular guy, twice, to a supposed GL1500 expert and it got better but had the flat spot. A mechanic (looked like he was not old enough to drive) in Kansas spotted the issue; a pin-hole in a diaphragm. Replaced the parts and it runs - perfect. Lots of so-called experts could not fnd the issue.

since i haven't really had a chance to ride it, i don't know what is NORMAL for these bikes. I had thought about replacing the seat but i'm now thinking a custom made seat may be in order. I'm a little thick and the wide front part of the seat causes my left leg to gramp almost imediatley.
I don't know how he cleaned the carbs or what he done with them but i'm running seafoam in my gas. 100 miles so far. Still a smooth ride.

What is normal is the engine runs super smooth and there are no flat-spots whatsoever. I ran enough seafoam through mine to fill a bathtub and it cured the off-idle issue quickly. The roll-on flat spot was the diaphram in the carb, once replaced, the machine (no longer mine) runs perfect. I met little brother in August in Dodge City and rode the 1500, it was nice. Ran perfect.

im also debating on weather to keep it or sell it. It is a beautiful bike but still needs minor things. Along with my left leg cramping, the engine gaurds get in the way of finding the brake pedal and the down shift peg. I also have a 1100 shadow and so far, it just seems like neither bike fits me.
I'll try to get things worked out on the goldwing. Maybe it is just a matter of getting used to it.

im also debating on weather to keep it or sell it. It is a beautiful bike but still needs minor things. Along with my left leg cramping, the engine gaurds get in the way of finding the brake pedal and the down shift peg. I also have a 1100 shadow and so far, it just seems like neither bike fits me.
I'll try to get things worked out on the goldwing. Maybe it is just a matter of getting used to it.

The first thing I'd try is to synchronize the carbs. If you can't get a steady vacuum level on the synch gauges on the TWO carbs at various rpms levels then you've got a vacuum leak, and most likely what I've just corrected and Fossil92 Bill corrected shortly before me. If you CAN hold a steady level on the vacuum gauges at various rpm levels, then you have a tight vacuum system and can synchronize the carbs.

"During times of universal deceit, telling the truth becomes a revolutionary act." ~ George Orwell